1. Field of the Invention
This invention relates to ribbed lenses for motor vehicle headlamps, and to moulding dies and methods for making such headlamp lenses.
2. The Prior Art
Such lenses usually include more than one zone of ribs, the ribs in the different zones being selected to produce different optical effects, usually differing degrees of lateral spreading, on the light passing through the lens. Where zones of ribs having different optical effects adjoin one another, there may be a discontinuity in the thickness of the lens, and this may produce disturbances in the pattern of illumination produced by the headlamp.